Recent data obtained from animal and human trials that expose dilated stenoses in arteries to both dilatation and ionizing radiation have shown that, after an extended time period such as six months, the section of the artery exposed to both dilatation and radiation exhibits the phenomena of late vascular contraction. A well known method to essentially eliminate late vascular contraction is to insert a stent into the artery at the site of the dilated stenosis.
Prior art radioisotope stents such as those described in U.S. Pat. No. 5,059,166 by R. E. Fischell, et al have been placed in both animal and human arteries. Although the results obtained from these studies have often shown very little cellular proliferation within the stent itself, especially at comparatively high activities for the radioisotope stent, there has been considerable vascular narrowing observed just beyond the edges of the stent. Much of this vascular narrowing is due to late vascular contraction that is caused by a combination of vascular trauma and a moderate level of radiation.